Item produced via injection molding

ABSTRACT

The present invention relates to (1) an item produced via injection molding comprising:
         i) from 50 to 85% by weight of a biodegradable polyester with MVR (190° C., 2.16 kg) to ISO 1133 of from 10 to 100 cm 3 /10 min comprising:
           a) from 90 to 99.5 mol % of succinic acid;   b) from 0.5 to 10 mol % of one or more C 8 -C 20  dicarboxylic acids; and   c) from 98 to 102 mol % of 1,3-propanediol or 1,4-butanediol;   
           ii) from 15 to 50% by weight of polylactic acid;   iii) from 10 to 50% by weight of at least one or more mineral fillers, where at least one filler is chalk;
 
and (2) processes for producing the abovementioned items.

The present invention relates to an item produced via injection moldingand comprising:

-   i) from 50 to 85% by weight, based on the total weight of components    i to ii, of a biodegradable polyester with MVR (190° C., 2.16 kg) to    ISO 1133 of from 10 to 100 cm³/10 min comprising:    -   a) from 90 to 99.5 mol %, based on components a to b, of        succinic acid;    -   b) from 0.5 to 10 mol %, based on components a to b, of one or        more C₈-C₂₀ dicarboxylic acids;    -   c) from 98 to 102 mol %, based on components a to b, of        1,3-propanediol or 1,4-butanediol;    -   d) from 0 to 0.1% by weight, based on components a to c, of a        chain extender or branching agent;-   ii) from 15 to 50% by weight, based on the total weight of    components i to ii, of polylactic acid;-   iii) from 10 to 50% by weight, based on the total weight of    components i to iv, of at least one or more mineral fillers, where    at least one filler is chalk;-   iv) from 0 to 2% by weight, based on the total weight of components    i to iv, of a nutrient salt mixture comprising at least two    components selected from the group consisting of:    nitrogen-containing cation or anion, sulfur-containing anion, and    phosphorus-containing anion and cation selected from the group    consisting of K⁺, Na⁺, Ca²⁺, Mg²⁺, and Fe^(2/3+).

The invention further relates to processes for producing theabovementioned items.

Filled biodegradable polymer mixtures which comprise a flexible polymersuch as an aliphatic-aromatic polyester (PBAT), and a rigid polymer,such as polylactic acid (PLA), are known from U.S. Pat. No. 6,573,340and WO 2005/063883. However, injection-molded items produced therefromare not always entirely satisfactory in terms of heat distortionresistance, stress-strain performance (modulus of elasticity), andbiodegradability.

DE 198 57 067 discloses monofilaments which comprise polybutylenesuccinate (PBS), polylactic acid, and talc. Said polymer mixtures haveinsufficient biodegradability for numerous injection-moldingapplications.

An objective of the present invention was therefore to provideinjection-molded items, or items produced via thermoforming, which donot have the abovementioned disadvantages. A particular objective was toprovide a sufficiently rigid plastic with heat resistance sufficient forapplications in the hot food and drinks sector. Biodegradability rateshould moreover be sufficiently high for certification to ISO 17088and/or EN 13432 and/or ASTM D6400 for an item with wall thicknesses offrom 50 μm to 2 mm.

Surprisingly, an item produced via injection molding and comprising:

-   i) from 50 to 85% by weight, based on the total weight of components    i to ii, of a biodegradable polyester with MVR (190° C., 2.16 kg) to    ISO 1133 of from 10 to 100 cm³/10 min comprising:    -   a) from 90 to 99.5 mol %, based on components a to b, of        succinic acid;    -   b) from 0.5 to 10 mol %, based on components a to b, of one or        more C₈-C₂₀ dicarboxylic acids;    -   c) from 98 to 102 mol %, based on components a to b, of        1,3-propanediol or 1,4-butanediol;    -   d) from 0 to 0.1% by weight, based on components a to c, of a        chain extender or branching agent;-   ii) from 15 to 50% by weight, based on the total weight of    components i to ii, of polylactic acid;-   iii) from 10 to 50% by weight, based on the total weight of    components i to iv, of at least one or more mineral fillers, where    at least one filler is chalk; and-   iv) from 0 to 2% by weight, based on the total weight of components    i to iv, of a nutrient salt mixture comprising at least two    components selected from the group consisting of:    nitrogen-containing cation or anion, sulfur-containing anion,    phosphorus-containing anion, and cation selected from the group    consisting of K⁺, Nat, Ca²⁺, Mg²⁺, and Fe^(2/3+),    has optimized mechanical properties, optimized heat distortion    resistance, and optimized biodegradation performance.

Components i to iii are in particular responsible for the interestingproperty profile of the item. Component i guarantees high heatresistance together with good biodegradability, component ii providesthe necessary rigidity and moreover improves biodegradability through asupplementary degradation mechanism. The mineral filler iii) improvesmechanical properties, such as modulus of elasticity, and heatdistortion resistance, and in particular in the case of chalk, promotesbiodegradability.

A more detailed description of the invention appears below.

The aliphatic polyesters i suitable for the invention have beendescribed in more detail in WO 2010/034711, which is expresslyincorporated herein by way of reference.

Polyesters i are generally composed of the following:

-   a) from 90 to 99.5 mol %, based on components a to b, of succinic    acid;-   b) from 0.5 to 10 mol %, based on components a to b, of one or more    C₈-C₂₀ dicarboxylic acids;-   c) from 98 to 102 mol %, based on components a to b, of    1,3-propanediol or 1,4-butanediol; and-   d) from 0 to 0.1% by weight, based on the total weight of components    a to c, of a chain extender or branching agent.

The copolyesters described are preferably synthesized in a directpolycondensation reaction of the individual components. The dicarboxylicacid derivatives here are reacted together with the diol in the presenceof a transesterification catalyst directly to give thehigh-molecular-weight polycondensate. On the other hand, it is alsopossible to obtain the polyester via transesterification of polybutylenesuccinate (PBS) with C₈-C₂₀ dicarboxylic acids in the presence of diol.Catalysts used usually comprise zinc catalysts, aluminum catalysts, andin particular titanium catalysts. An advantage of titanium catalysts,such as tetra(isopropyl) orthotitanate and in particular tetraisobutoxytitanate (TBOT) over the tin catalysts, antimony catalysts, cobaltcatalysts, and lead catalysts often used in the literature, for exampletin dioctanoate, is that any residual amounts of the catalyst ordownstream product from the catalyst that remain within the product areless toxic. This is a particularly important factor in biodegradablepolyesters because they pass into the environment by way of example inthe form of composting bags or mulch films.

A mixture of the dicarboxylic acids is generally first heated in thepresence of an excess of diol together with the catalyst to an internaltemperature of from 170 to 230° C. within a period of about 60-180 min,and resultant water is removed by distillation. The melt of theresultant prepolyester is then usually condensed at an internaltemperature of from 200 to 250° C. within the period of from 3 to 6hours at reduced pressure while the diol liberated is removed bydistillation until the desired viscosity has been achieved withintrinsic viscosity (IV) from 50 to 450 mL/g and preferably from 95 to200 mL/g.

The copolymers of the invention can also be produced by the processesdescribed in WO 96/15173 and EP-A 488 617. It has proven advantageous tobegin by reacting components a to c to give a prepolyester with IV from50 to 100 mL/g, preferably from 60 to 80 mL/g, and then to react thiswith chain extenders d, for example with diisocyanates or withepoxy-containing polymethacrylates, in a chain extension reaction togive a polyester with IV from 50 to 450 mL/g, preferably from 95 to 200mL/g.

Acid component a used comprises from 90 to 99.5 mol %, based on acidcomponents a and b, preferably from 91 to 99 mol %, and with particularpreference from 92 to 98 mol %, of succinic acid. Succinic acid isaccessible by a petrochemical route, or else preferably from renewableraw materials, for example as described in PCT/EP2008/006714.PCT/EP2008/006714 discloses a biotechnological process for producingsuccinic acid and 1,4-butanediol starting from various carbohydrates andusing microorganisms from the Pasteurellaceae family.

The amount used of acid component b is from 0.5 to 10 mol %, preferablyfrom 1 to 9 mol %, and with particular preference from 2 to 8 mol %,based on acid components a and b.

The expression C₈-C₂₀ dicarboxylic acids b in particular meansterephthalic acid, suberic acid, azelaic acid, sebacic acid, brassylicacid and/or arachidonic acid. Preference is given to suberic acid,azelaic acid, sebacic acid and/or brassylic acid. The abovementionedacids, inclusive of terephthalic acid, are accessible from renewable rawmaterials. By way of example, sebacic acid is accessible from castoroil. Polyesters of this type feature excellent biodegradationperformance [reference: Polym. Degr. Stab. 2004, 85, 855-863].

The dicarboxylic acids a and b can be used either in the form of freeacid or in the form of ester-forming derivatives. Particularester-forming derivatives that may be mentioned are the di-C₁- toC₆-alkyl ester, such as dimethyl, diethyl, di-n-propyl, diisopropyl,di-n-butyl, diisobutyl, di-tert-butyl, di-n-pentyl, diisopentyl, ordi-n-hexyl ester. Anhydrides of the dicarboxylic acids can also be used.

The dicarboxylic acids or ester-forming derivatives thereof can be usedindividually or in the form of a mixture here.

The diols 1,3-propanediol and 1,4-butanediol are also accessible fromrenewable raw materials. It is also possible to use a mixture of the twodiols. 1,4-Butanediol is preferred as diol because of the higher meltingpoints and the better crystallization of the resultant copolymer.

At the start of the polymerization reaction, the ratio of the diol(component c) to the acids (components a and b) is generally adjusted sothat the ratio of diol to diacids is from 1.0 to 2.5:1 and preferablyfrom 1.3 to 2.2:1. Excess amounts of diol are drawn off during thepolymerization reaction so that the ratio obtained at the end of thepolymerization reaction is approximately equimolar. The expressionapproximately equimolar means a diol/diacids ratio of from 0.90 to 1.10.

Use is generally made of from 0 to 1% by weight, preferably from 0.01 to0.9% by weight, and with particular preference from 0.1 to 0.8% byweight, based on the total weight of components a to b, of acrosslinking agent d and/or chain extender d′ selected from the groupconsisting of: a polyfunctional isocyanate, isocyanurate, oxazoline,carboxylic anhydride, such as maleic anhydride, epoxide (in particularan epoxy-containing poly(meth)acrylate), an at least trihydric alcohol,or an at least one tribasic carboxylic acid. Chain extenders d′ used cancomprise polyfunctional, and in particular difunctional, isocyanates,isocyanurates, oxazolines, or epoxides.

Chain extenders and alcohols or carboxylic acid derivatives having atleast three functional groups can also be considered to be crosslinkingagents. Particularly preferred compounds have from three to sixfunctional groups. Examples that may be mentioned are: tartaric acid,citric acid, malic acid, trimesic acid, trimellitic acid, trimelliticanhydride, pyromellitic acid, and pyromellitic dianhydride;trimethylolpropane, trimethylolethane; pentaerythritol, polyethertriols,and glycerol. Preference is given to polyols, such astrimethylolpropane, pentaerythritol, and in particular glycerol. Byusing components d it is possible to construct pseudoplasticbiodegradable polyesters. The rheological behavior of the meltsimproves; the biodegradable polyesters have better processability, forexample better drawability to give films via melt solidification. Thecompounds d have a shear-thinning effect, i.e. they make the polymermore pseudoplastic. Viscosity decreases under load.

It is generally advisable to add the crosslinking (at leasttrifunctional) compounds to the polymerization reaction at a relativelyearly juncture.

Examples of suitable bifunctional chain extenders are tolylene2,4-diisocyanate, tolylene 2,6-diisocyanate, diphenylmethane2,2′-diisocyanate, diphenylmethane 2,4′-diisocyanate, diphenylmethane4,4′-diisocyanate, naphthylene 1,5-diisocyanate, and xylylenediisocyanate, hexamethylene 1,6-diisocyanate, isophorone diisocyanate,and methylenebis(4-isocyanatocyclohexane). Particular preference isgiven to isophorone diisocyanate and in particular hexamethylene1,6-diisocyanate.

The number-average molar mass (Mn) of the polyesters i is generally inthe range from 8000 to 100 000 g/mol, in particular in the range from8000 to 50 000 g/mol, and their weight-average molar mass (Mw) isgenerally from 10 000 to 300 000 g/mol, preferably from 10 000 to 120000 g/mol, and their Mw/Mn ratio is generally from 1 to 6, preferablyfrom 2 to 4. Intrinsic viscosities from 30 to 450 g/mL, preferably from50 to 200 g/mL (measured in o-dichlorobenzene/phenol (ratio by weight50/50)). Melting point is in the range from 85 to 130, preferably in therange from 95 to 120° C.

The rigid component ii is polylactic acid (PLA).

It is preferable to use polylactic acid with the following propertyprofile:

-   -   a melt volume rate (MVR for 190° C. and 2.16 kg to ISO 1133 of        from 0.5 to 40 ml/10 minutes, in particular from 15 to 25 ml/10        minutes)    -   melting point below 240° C.;    -   glass transition temperature (Tg) above 55° C.    -   water content smaller than 1000 ppm    -   residual monomer content (lactide) smaller than 0.3%    -   molecular weight greater than 80 000 daltons.

Examples of preferred polylactic acids are NatureWorks® Ingeo 6201 D,6202 D, 6251 D, 3051 D, and in particular 3051 D or 3251 D, and alsocrystalline polylactic acids from NatureWorks.

The percentage proportion by weight used of the polylactic acid ii,based on components i and ii, is from 15 to 50%, preferably from 15 to45%, and with particular preference from 20 to 40%. It is preferablehere that the polylactic acid ii forms the dispersed phase and that thepolyester i forms the continuous phase or is part of a co-continuousphase. Polymer mixtures with polyester i in the continuous phase or aspart of a co-continuous phase have higher heat distortion resistancethan polymer mixtures in which polylactic acid ii forms the continuousphase.

The amount used of at least one mineral filler selected from the groupconsisting of: chalk, graphite, gypsum, conductive carbon black, ironoxide, calcium chloride, dolomite, kaolin, silicon dioxide (quartz),sodium carbonate, titanium dioxide, silicate, wollastonite, mica,montmorillonites, talc powder, and mineral fibers is generally from 10to 50% by weight, in particular from 10 to 40%, and particularlypreferably from 10 to 35%, based on the total weight of components i toiv.

Interestingly, it has been found that addition of chalk can achieve afurther improvement in the biodegradability of the items. The chalk isessential as filler in the mixtures of the invention. The amount ofchalk added is preferably from 5 to 35% by weight, with preference from8 to 30% by weight, with particular preference from 10 to 20% by weight,based on the total weight of components i to iv. Talc powder in turn canprovide greater effectiveness in terms of increasing modulus ofelasticity and improving heat distortion resistance. The combination ofchalk and talc powder is particularly preferred as filler.

Mixtures of talc powder and chalk have proven particularly advantageous.A mixing ratio that has proven advantageous here is from 1:5 to 5:1,preferably from 1:3 to 3:1, and in particular from 1:2 to 1:1.

For the purposes of the present invention, a substance or substancemixture complies with the “biodegradable” feature if the percentagedegree of biodegradation of said substance or the substance mixture toDIN EN 13432 is at least 90% after 180 days.

Biodegradbility generally leads to decomposition of the polyesters orpolyester mixtures in an appropriate and demonstrable period of time.The degradation can take place by an enzymatic, hydrolytic, or oxidativeroute, and/or via exposure to electromagnetic radiation, such as UVradiation, and can mostly be brought about predominantly via exposure tomicroorganisms, such as bacteria, yeasts, fungi, and algae.Biodegradability can be quantified by way of example by mixing polyesterwith compost and storing it for a particular period. By way of example,in DIN EN 13432 (with reference to ISO 14855), CO₂-free air is passedthrough ripened compost during the composting process, and the compostis subjected to a defined temperature profile. Biodegradability here isdefined as a percentage degree of biodegradation, by taking the ratio ofthe net amount of CO₂ released from the specimen (after subtraction ofthe amount of CO₂ released by the compost without specimen) to themaximum amount of CO₂ that can be released from the specimen (calculatedfrom the carbon content of the specimen). Biodegradable polyesters orbiodegradable polyester mixtures generally exhibit clear signs ofdegradation after just a few days of composting, examples being fungalgrowth, cracking, and perforation.

Other methods of determining biodegradability are described by way ofexample in ASTM D5338 and ASTM D6400-4.

Injection molding involves a shaping process which is very frequentlyused in plastics processing. Injection molding can produce large numbersof directly usable moldings extremely cost-effectively. In simplifiedterms, the process functions as follows: the respective thermoplasticmaterial (“molding composition”) is melted in an injection-moldingmachine composed of a heatable cylinder in which a screw rotates, and isinjected into a metal mold. The cavity of the mold determines the shapeand the surface structure of the finished part. It is now possible toproduce parts weighing from significantly below one gram up todouble-digit kilograms.

Injection molding can produce consumer articles with high precisionquickly and cost-effectively. The nature of the surface of therespective component here can be selected by the designers with almostno restriction. A wide variety of surface structures can be produced,from smooth surfaces for optical applications to graining for regionsthat are pleasant to touch, through to patterns or engraved effects.

Cost-effectiveness reasons make the injection molding processparticularly suitable for producing relatively large numbers of units,since the costs for the injection mold themselves represent aconsiderable proportion of the capital investment required. Even in thecase of simple molds, the purchase cost is not recouped until severalthousand parts have been produced.

Particularly suitable materials for injection molding are polymermixtures of components i to iv with MVR (190° C., 2.16 kg) to ISO 1133of from 10 to 100 cm³/10 min, preferably from 10 to 80 cm³/10 min and inparticular from 25 to 60 cm³/10 min. Materials which have provensuitable in these polymer mixtures are moreover in particularly linearor only slightly branched polyesters which comprise from 0 to 0.1% byweight, based on components a to c, of a branching agent.

Performance Tests:

The molecular weights Mn and Mw of the semiaromatic polyesters weredetermined by means of SEC to DIN 55672-1: eluent hexafluoroisopropanol(HFIP)+0.05% by weight of potassium trifluoroacetate; narrowlydistributed polymethyl methacrylate standards were used for calibration.

Intrinsic viscosities were determined to DIN 53728 part 3, Jan. 3, 1985,Capillary viscometry. An M-II micro-Ubbelohde viscometer was used. Thesolvent used comprised a phenol/o-dichlorobenzene mixture in a ratio byweight of 50/50.

Modulus of elasticity was determined by means of a tensile test onpressed films of thickness about 420 μm to ISO 527-3: 2003.

Charpy impact resistance was determined to ISO 179-2/1eU:1997. The testspecimen (80 mm×10 mm×4 mm) in the form of a horizontal bar supportedclose to its ends is subjected to a single pendulum impact, the impactline being in the middle between the two test-specimen supports, and ahigh, nominally constant bending velocity (2.9 or 3.8 m/s) is used (onthe specimen).

HDT-B heat distortion resistance was determined to ISO 75-2:2004. Astandard test specimen is subjected to three-point bending underconstant load, thus producing a flexural stress (HDT/B 0.45 MPa) asstated in the relevant part of said international standard. Thetemperature is increased at uniform rate (120 K/h), and the temperaturevalue measured is that at which a defined standard deflection isachieved, corresponding to the defined increase in flexural strain(0.2%).

The degradation rates of the biodegradable polyester mixtures and of themixtures produced for comparison were determined as follows:

Films were produced from the biodegradable polyester mixtures and fromthe mixtures produced for comparison, in each case via pressing at 190°C. and with thickness of 400 μm. In each case, these foils were cut intorectangular pieces with edge lengths of 2×5 cm. The weight of said filmpieces was determined. The film pieces were heated to 58° C. in an ovenin a plastics container containing moistened compost, for a period offour weeks. At weekly intervals the residual weight of each piece offilm was measured. On the assumption that biodegradation can beconsidered in these instances to be purely a surface process, thegradient of the resultant weight reduction (biodegradation rate) wasdetermined by calculating the difference between the weight measuredafter taking of a sample and the mass of the film before the start ofthe test, less the average total weight reduction that occurred up tothe taking of the preceding specimen. The mass reduction obtained wasalso standardized for surface area (in cm²) and also for time betweentaking of current and previous specimen (in d).

The degradation rates determined were based on the degradation rate ofPBS (=100%).

Starting Materials

Polyester i:

a) Polylbutylene succinate (Comparative System)

First, butanediol (93.7 g, 130 mol %), succinic acid (94.5 g, 100 mol%), and 0.2 g of glycerol (0.1% by weight) were heated to 200° C. in thepresence of tetrabutyl orthotitanate TBOT (0.2 g), and the resultantwater was removed by distillation during a period of 30 min. Thisprepolyester was then reacted at reduced pressure (<5 mbar) to give thehigh-molecular-weight polyester. For this, 1,4-butanediol was removed bydistillation up to a temperature of 250° C. The IV of the resultantpolyester was 171 mL/g.

b) Polybutylene succinate-co-suberate (succinic acid:suberic acid=90:10)

Butanediol (85.0 g, 130 mol %), succinic acid (77.1 g, 90 mol %), andsuberic acid (12.6 g, 10 mol %), and 0.18 g of glycerol (0.1% by weight)were first heated to 200° C. in the presence of TBOT (0.2 g). The meltwas kept at this temperature during a period of 80 min. 1,4-Butanediolwas then removed by distillation at reduced pressure (<5 mbar) and at amaximum internal temperature of 250° C. The polyester was decanted andanalyzed after cooling. The intrinsic viscosity of the resultantpolyester was 170 mL/g.

c) Polybutylene succinate-co-sebacate (succinic acid:sebacic acid=95:5)

Butanediol (89.0 g, 130 mol %), succinic acid (85.3 g, 95 mol %), andsebacic acid (7.7 g, 5 mol %), and 0.14 g of glycerol (0.1% by weight)were first heated to 200° C. in the presence of TBOT (0.2 g). The meltwas kept at this temperature during a period of 80 min. 1,4-Butanediolwas then removed by distillation at reduced pressure (<5 mbar) and at amaximum internal temperature of 250° C. The polyester was decanted andanalyzed after cooling. The intrinsic viscosity of the resultantpolyester was 214 mL/g.

d) Polybutylene succinate-co-sebacate (succinic acid:sebacic acid=90:10)

Butanediol (87.5 g, 130 mol %), succinic acid (79.4 g, 90 mol %), andsebacic acid (15.1 g, 10 mol %), and 0.19 g of glycerol (0.1% by weight)were first heated to 200° C. in the presence of TBOT (0.2 g). The meltwas kept at this temperature during a period of 80 min. 1,4-Butanediolwas then removed by distillation at reduced pressure (<5 mbar) and at amaximum internal temperature of 250° C. The polyester was decanted andanalyzed after cooling. The intrinsic viscosity of the resultantpolyester was 252 mL/g.

e) Polybutylene succinate-co-azelate (succinic acid:azelaic acid=90:10)

Butanediol (92.0 g, 130 mol %), succinic acid (83.4 g, 90 mol %), andazelaic acid (14.8 g, 10 mol %), and 0.19 g of glycerol (0.1% by weight)were first heated to 200° C. in the presence of TBOT (0.2 g). The meltwas kept at this temperature during a period of 80 min. 1,4-Butanediolwas then removed by distillation at reduced pressure (<5 mbar) and at amaximum internal temperature of 250° C. The polyester was decanted andanalyzed after cooling. The intrinsic viscosity of the resultantpolyester was 214 mL/g.

f) Polybutylene succinate-co-brassylate (succinic acid:brassylicacid=90:10)

Butanediol (85 g, 130 mol %), succinic acid (77.1 g, 90 mol %), andbrassylic acid (18.1 g, 10 mol %), and 0.17 g of glycerol (0.1% byweight) were first heated to 200° C. in the presence of TBOT (0.2 g).The melt was kept at this temperature during a period of 80 min.1,4-Butanediol was then removed by distillation at reduced pressure (<5mbar) and at a maximum internal temperature of 250° C. The polyester wasdecanted and analyzed after cooling. The intrinsic viscosity of theresultant polyester was 160 mL/g.

g) Polybutylene succinate-co-terephthalate (succinic acid:terephthalicacid=90:10)

Butanediol (90.8 g, 130 mol %), succinic acid (82.4 g, 90 mol %), anddimethyl terephthalate (15.0 g, 10 mol %), and 0.18 g of glycerol (0.1%by weight) were first heated to 200° C. in the presence of TBOT (0.2 g).The melt was kept at this temperature during a period of 80 min.1,4-Butanediol was then removed by distillation at reduced pressure (<5mbar) and at a maximum internal temperature of 250° C. The polyester wasdecanted and analyzed after cooling. The intrinsic viscosity of theresultant polyester was 172 mL/g.

To determine biodegradability, a molding press was used to produce filmsof thickness about 420 μm.

TABLE 1 Biodegradation rate measured on the basis of mass loss from amolding, standardized for the surface area of the molding. Relative toPBS (=100%): Rel. degradation rate Example Material (standardized massloss) [%] a PBS 100 b PBSSub 10% 450 c PBSSe 5% 300 d PBSSe 10% 700 ePBSAz 10% 850 f PBSBry 10% 1000 g PBST 10% 260

Polylactic acid ii-1: 4043D from NatureWorks

Mineral Fillers

iii-1: chalk from Omya

iii-1: talc powder from Mondominerals

EXAMPLES I) Production of Polymer Mixtures

General Specification (GS1)

Polymer blends COMP1 and COMP2 were produced by a corotating twin-screwextruder from Coperion. The screw diameter was 26 mm, and the L/D ratioof the extruder was 40. The extrusion temperature was from 150° C. to240° C. The polymer was charged at room temperature to zone 0. Forinventive examples 3 to 5, the same extruder was used with the sameproduction conditions. The fillers were fed by hot feed to zone 4. Thesubsequent zones 5 and 6 served for dispersion. The material wasdevolatilized in zones 7 and 8 and zone 9 served for discharge.

TABLE 2 Compounded materials produced via GS1; data in percent by weightPBSSe Talc Example PBS (5 mol % Se) PLA powder Chalk Comp-1 70 30 Comp-255 45 Comp-3 49 21 30 4 49 21 30 5 49 21 20 10

II) Production of Moldings

The test specimens used were produced by injection molding at melttemperatures of from 150 to 200° C. and at a mold temperature from roomtemperature to 60° C. The tests used standard test specimens asspecified in ISO 20753. Disintegration rates were determined on plaquesof dimensions 60×60×1 mm³.

TABLE 3 Relative disintegration rate of various polyester/PLS mixtures -without filler Disintegration rate, Example Material relative [%] Comp-1PBS/PLA (70:30) 100 M-c PBSSe (5% Se)/PLA (70:30) 240 M-d PBSSe (10%Se)/PLA (70:30) 714 M-g PBST (5% T)/PLA (70:30) 110

The relative disintegration rate of various polyester/PLA blends wasstudied by incubating each of 30 moldings (plaques, 60×60×1 mm³) incompost for 12 weeks. After incubation, the amounts of plastics residuesremaining in the material that does not pass through the sieve werecompared and used to determine the relative disintegration rate, and arelisted in Table 3.

TABLE 4 Thermal and mechanical data for the polyester/polyestermixtures, based on moldings (plaques, 60 × 60 × 1 mm³ to ISO 20753)Modulus of Charpy, elasticity^(a) unnotched^(b) HDT-B^(c) ExampleMaterial [MPa] [kJ/m²] [° C.] a PBS 569 n.d. 89 c PBSSe 5% 440 n.d. n.d.d PBSSe 10% 395 n.d. n.d. g PBST 10% 378 n.d. n.d. Comp-1 PBS + PLA(70:30) 1106 218 71 Comp-2 PBS + PLA (55:45) 1511 252 55 Comp-3 PBSSe5% + PLA + 3256 42 90 talc powder (49:21:30) 4 PBSSe 5% + PLA + 1597 18073 chalk (49:21:30) 5 PBSSe 5% + PLA + 2776 46 88 talc powder + chalk(49:21:20:10) ^(a)Modulus of elasticity to ISO 527-3: 2003 ^(b)Charpyimpact resistance to ISO 179-2/1eU: 1997 ^(c)HDT-B to ISO 75-2: 2004

The results listed in Table 4 show that the moldings produced from themixtures 4 and 5 of the invention exhibit a very advantageouscombination of mechanical properties (high modulus of elasticity) andthermal properties (good heat distortion resistance).

TABLE 5 Degradation measurements to ISO 17088 (2008) on plaques (60 × 60× 1 mm) Degradation standard Example Degradation after 12 weeks ISO17088 Comp-3 Inadequate degradation Non-compliant Ø particle size 2 × 2cm 4 Almost complete degradation Compliant Ø particle size 1 × 1 cm

At the same time, the results in Table 5 show an improved degradationrate for the mixtures of the invention.

1-6. (canceled)
 7. An item produced via injection molding comprising: i)from 50 to 85% by weight, based on the total weight of components i) toii), of a biodegradable polyester with MVR (190° C., 2.16 kg) to ISO1133 of from 10 to 100 cm³/10 min comprising: a) from 90 to 99.5 mol %,based on components a) to b), of succinic acid; b) from 0.5 to 10 mol %,based on components a) to b), of one or more C₈-C₂₀ dicarboxylic acids;c) from 98 to 102 mol %, based on components a) to b), of1,3-propanediol or 1,4-butanediol; d) from 0 to 0.1% by weight, based oncomponents a) to c), of a chain extender or branching agent; ii) from 15to 50% by weight, based on the total weight of components i) to ii), ofpolylactic acid; iii) from 10 to 50% by weight, based on the totalweight of components i) to iv), of at least one or more mineral fillers,where at least one filler is chalk; iv) from 0 to 2% by weight, based onthe total weight of components i) to iv), of a nutrient salt mixturecomprising at least two components selected from the group consistingof: nitrogen-containing cation or anion, sulfur-containing anion,phosphorus-containing anion, and cation selected from the groupconsisting of K⁺, Na⁺, Ca²⁺, Mg²⁺, and Fe²¹³⁺.
 8. The item according toclaim 7, where component b) in polyester i) is a dicarboxylic acidselected from the group consisting of suberic acid, azelaic acid,sebacic acid, and brassylic acid.
 9. The item according to claim 7,where polyester i) forms the continuous phase or part of a co-continuousphase.
 10. The item according to claim 7, where filler iii) is a mixtureof talc powder and chalk in a ratio of from 1:5 to 5:1.
 11. The itemaccording to claim 7, wherein the item has a wall thickness of from 50μm to 2 mm.
 12. The item according to claim 7, wherein the item has amodulus of elasticity to ISO 527-3 of from 1200 to 4500 MPa and with anHDT-B temperature to ISO 75-2 of from 60 to 115° C.